For anybody who has and will see David Michôd's "The Rover," there's another strong lead besides Robert Pattinson and Guy Pearce: its soundtrack is like another character. The score for the film was composed by Antony Partos and performed by sound designer Sam Petty. (They both also helmed the sounds for Michôd's "Animal Kingdom.")

Michôd initially presented his cast with previously recorded and powerful songs from accomplished saxophonists and composers Colin Stetson and William Basinski, post-rockers Tortoise, Italian composer Giacinto Scelsi and -- yup -- pop star Keri Hilson. Partos and Petty chewed on them too, and riffed on the descending scenery for Pattinson's Rey and Pearce's Eric. What they weaved in became a gorgeous black mass of ominous, dissonant, agitated and aggressive compositions to rove to in the Australian outback.

Today, we exclusively reveal "The Rover" score tracks on their own; below, Michôd and Partos discuss arriving at sounds, customizing bastardized violins, the Keri Hilson "Pretty Girl Rock" scene, and when to try a little tenderness.

David, you had given songs from Colin Stetson, Tortoise, etc. to the cast as "mood signifiers." Had you always known that you definitely wanted some of those songs to end up in the movie too? What was your vision of how those songs would blend with Antony and Sam's original work, or was that planned?

David Michôd: I find music the the clearest and easiest way in to what a movie will feel like - more so than visual references or other movies or dense dossiers of research material. Every now and then I'll send a piece of music or two to people I'm working with -- actors or heads of department - when I think it'll help them get a sense of the kind of movie I'm proposing. Often those pieces will end up in the movie -- sometimes they won't. I build big playlists while I'm writing -- stuff from all over the place, stuff I suspect I'll never use -- and then, as we get closer to production and then the edit, I whittle that list down to the key pieces that somehow embody the movie and its key scenes.

So, yeah, those tracks -- the Stetson, Basinski, Tortoise etc -- were ones I had hoped would find their way into the finished cut. I always knew, however, that there would be strange gaps that needed to be filled -- connecting tissues or pieces requiring something very specific that I hadn't been able to find. That's where the exceptional talents of Antony Partos and Sam Petty come in.

What were the other songs you could have potentially gone with for Robert/Rey's "Pretty Girl Rock" scene? Why and how did you settle on that one?

Michôd: I think once upon a time I had "Don't Cha" by The Pussycat Dolls down for that scene. It was just a signpost in the script. I can't remember how and when Keri Hilson found herself in the mix. I wanted that moment in the movie to function as a potent reminder of the fact that Rob's character is a kid who in different circumstances would just be doing the kinds of things kids do everywhere -- thinking about girls, playing with his hair, listening to music. Instead, he has found himself in the middle of nowhere, tethered to a monstrously damaged drifter.

Antony, can you elaborate how, logistically, you and Sam would split or perform various "duties" for this? Did you call dibs on characters you wanted to write themes for, or were did you assign yourselves specific instruments one or the other would play? Or was it important that everything was created together?

Antony Partos: Working together with David and Sam again after "Animal Kingdom" made it possible to have a certain short hand in terms of decision making.

In a sense this was much a simpler process than with "Animal Kingdom." David had a very strong vision for the musical palette and also distinct ideas about what should be in Sam's domain and what should be score. Sam works a lot of with tonal based textures and is a very nuanced sound designer. In terms of forming a stream lined process on "The Rover," I would send over temp mixes to Sam, so things like key, could be established early on. I also sent over individual musical based sounds for Sam to use as he saw fit.

Aside from being fairly ambient, there's also a very minimal, primitive vibe to the score, an obvious reflection of the visuals.  Did you set certain restrictions or parameters (aside from time cues) in which you could only operate in creating (or selecting) the music -- like number of allowed instruments, types of instruments, keys/tones?

Partos: David was always intent on using some pieces by the extraordinary saxophonist Colin Stetson, so this really set the tone and palette early on in the piece. My brief was to try and evoke a certain sadness and help the two main characters develop an unspoken bond. I was interested in complimenting Colin's pieces by also using saxophones so I created pieces by getting musicians in early on to play in unusual ways. For example, recording baritone and bass saxophones not only in their usual register but also getting them to play harmonics and notes at the extreme high end of the register. I would also play with the pitches after the record by manipulating elements octaves below or higher than their original pitch. This help create a mood that was somehow tender but simultaneously alien. Similar techniques were used with bass Irish whistles and strings.

The string work was recorded individually and used a combination of bastardized custom made violins with strings that could play in either viola or cello pitch as well as electric violin. Once again it help create a mood that was subtly emotional but somehow unfamiliar and lonely.

Music like from the "Homecoming" scene can be downright hopeful, something this movie isn't really about. Were there times you knew you wanted to lighten the film up, even when the story kept going down, down, down?

Partos: My task was to build the trust and love between the two main characters despite their circumstances. I think there is a subtle yet tangible shift that develops two thirds of the way through the story and the score does change in this regard to become more harmonically based compared to the textures that are present in the first half of the film. It was interesting to see how it played with a large audience. There are certain moments in the film that give it relief. This was evident in the script and it was picked up by the audience in the Sydney Film Festival screening.

Yes the film is dark -- and I must admit for me I am drawn to a sense of broodiness with my music. But hopefully there is an aspect to tenderness in the score as well.

Some of the abstract samples or scores are like loops, good palate cleansers (or good for brain entropy when you're in a rut). What music or audio do you use to bring order to your creative life? What do you do to mess it all up?

Partos: My life is naturally disorganized. I struggle to bring order to it at the best of times. I think I am wired in a more chaotic manner than most, and I do my best to hide this fact from as many people as possible!